Tabletting presses



y 1961 E. cum-[us 2,992,729

TABLETTING PRESSES Filed May 15, 1956 2 Sheets-Sheet 1 EJ mun Curt,

INVENTOR.

A0 BY July 18, 1961 E. CURTIUS 2,992,729

TABLETTING PRESSES Filed May 15, 1956 2 Sheets-Sheet 2 EJ numl Curt: US

.INVENTOR.

Patented July 18, 1961 2,992,729 TABLETTING PRESSES Edmund Curtius,Cologne-Weidenpesch, Germany, assignor to Kilian & Co. G.m.b.H.,Cologne-Niehl, Ger many, a German company Filed May 15, 1956, Ser. No.585,078

Claims priority, application Germany May 21, 1955 7 Claims. (Cl. 209-79)This invention relates to apparatus for compressing a coating ofpowdered material around a preformed core.

It is known per se for cored tablets to be manufactured on rotatabletabletting presses. In such cases, a bottom layer or fill of the coatingmaterial is first introduced into a die apparatus on top of a lowerpunch and initially compressed.

A core which has been made independently on a separate machine is thenlaid in position on top of the bottom fill. Finally, after suitablecontinued descending movement of the lower punch, a top coating layer orfill is introduced into the die aperture and the whole is then pressedbetween the lower punch and an upper punch so that a sufficientconsolidation of the coating material is obtained and the margins of thetwo outer layers covering the core are firmly united with one another.

It may occasionally happen that, for some reason or other, no coretablet is placed in a die aperture so that an imperfect tabletconsisting entirely of coating material is produced and must bediscarded. However, this presents some difficulty, since the absence ofa core cannot be detected by visual inspection.

An object of the present invention is to provide a device which iscontrolled by the compression pressure so as to detect such imperfecttablets and eject them separately. The control of the device for theseparate ejection of imperfect, coreless tablets may be effected by apressureequalizing roller for the bottom punches of the apparatus, whichroller is arranged in a pressing zone and is resiliently supported. Whena normal tablet is guided in its die aperture for final shaping over thepressureequalizing roller, the bottom fill of coating has been initiallycompressed and the core has been finally compressed. Consequently, it isonly a final pressing of the upper fill of coating material which takesplace. Because the upper fill is comparatively small, thepressure-equalizing roller is forced back a comparatively largedistance. However, the conditions are somewhat difi'erent if no core hasbeen introduced into the die aperture as in such case, it is alsonecessary for that part of the coating material which takes the place ofthe absent core to be compressed. In this case, there is a lessextensive retraction of the pressure-equalizing roller since the coatingmaterial is introduced in measured amounts and there is less material inthe die aperture when no core is present.

The pressure-equalizing roller may be supported by links or by any othersupporting device which in turn is resiliently retracted. The supportingdevice can, in a simple manner, be made to actuate a switch from whichis operated a storage mechanism which in turn subsequently controls theadjustable ejection device. The ejection may be effected, for example,by two stripper devices arranged one behind the other in the directionof rotation of the die plate or table, it being possible to move thefirst of these stripper devices at will into and out of its operativeposition, the second being fixed.

The storage mechanism can consist of a disc rotating with the die plateor table and provided with electric condensers. Adjacent this disc, is acharging contact which receives electric current from a current sourceas long as a micro-switch controlled by the compression pressure in thepreparation of the tablets is closed; The

arrangement can be such that the micro-switch is closed.

when the compression pressure is too weak so that, under theseconditions, the condenser just moving past the charging contact ischarged. Moreover, a discharging contact for discharging the condenseris also arranged at a suitable point adjacent the rotatable disc and inturn controls a relay which controls the adjustable stripper device forremoving the tablets from the die plate or table. This dischargingcontact is arranged at a distance from the charging contact whichcorresponds to the spacing between the pressing station and the ejectingstation. In the time in which a condenser, charged because of thepressing of a coreless tablet, has been advanced from the chargingstation at the chargiing contact to the ejecting station at thedischarging contact, the coreless tablet has also moved as far as theejecting station. Owing to the operation of the movable stripper device,the coreless tablet is then ejected separately from the other tablets,i.e. the tablets containing cores.

It is necessary that the movable stripper should be held in its strippedposition for a time, in practice, during one shifting movement of thedie plate. In order to achieve this, the relay operated by the dichargecontact closes an additional circuit in which the relay itself isarranged in addition to closing the circuit of a solenoid for thestripper. As the relay has been closed through the discharge contact, itremains in the closed position until the holding circuit is in turnbroken by a circuit breaker which is held in the closed position by alever applied by pressure (for example, the pressure of a travellingpunch), for a period of time which is necessary for the coreless tabletto pass through the stripper.

If a tablet without a core is compressed, the corresponding controlimpulse is recorded by the storage mechanism and subsequently used forthe control of the movable stripper device in such manner that, forexample, all normal tablets containing a core are ejected by the movablestripper, but that the stripper is lifted out of the path of movement ofthe tablets on the arrival of a coreless tablet. This coreless tabletthen travels in front of the fixed stripper device which ejects into aseparate collecting means.

An embodiment of the invention is shown by way of example in theaccompanying drawings in which:

FIGURE 1 is a side elevation of the pressing portion of a rotatabletabletting press,

FIGURE 2 is an enlarged vertical cross-section of a cored tablet,

FIGURE 3 is a corresponding plan view, substantially on the line 33 ofFIGURE 1,

FIGURE 4 is a side elevation corresponding to FIG- URE 1, but seen fromanother direction, and

FIGURE 5 is a plan view of the pressing and discharge zones of the dieplate or table with a storage mechanism.

As shown in the drawings, a cored tablet 10 consists of a bottom coating11, a core 12 and a top coating 13.

To produce such a tablet a measured quantity of comminuted coatingmaterial for the bottom layer 11 is introduced into one of a number ofdie apertures 14 (FIGURE 3) of the die plate or table 15 of a rotatabletabletting press. The core 12 is laid in position in the die aperturewhen the bottom layer or fill is in position. This may be efiected by adepositing plate or table 16 (which is diagrammatically indicated inFIGURE 3) or by any other suitable means. The coating material for thetop layer or fill 13 is then, introduced into the die aperture. Thetablet 10 is then compressed as a unit at high pressure. The pressing iseffected in the vertical die apertures 14. of the die plate or table 15between bottom punches 17 and top punches 18 there being a guide track17 below and in contact with the lower ends of bottom punches 17. Themaximum compression pres- I 'sure is produced in a pressing zone, shownat the center of FIGURE 4, in which the bottom punch 17 travels over apressure-equalizing roller 19 while the top punch 18 is moved downwardlyto its lowest end position. The equalizing roller 19 is mounted onbell-crank 20, an arm 21 of which is loaded by a supporting spring 22.The arm 21 also carries an electrical contact lever 23 which can touchan opposite contact 24 when the equalizing roller 19 has been forcedback a sufiicient distance.

If a core 12 has been correctly deposited in the die aperture 14 by thedistributing plate 16, the equalizing roller 19 in the pressing zone isretracted in the downward direction for a large distance. Theconsequence of this movement is that the contacts 23 and 24 come intoengagement. On the other hand, if the tablet in the die aperture is animperfect one which does not contain any core the same downward presingmovement of the top punch 18, acting through the bottom punch 17,retracts the pressu-re-eq-ualizing roller to a smaller extent, becausethe die aperture contains less material.

On each occasion that a tablet passes the pressing zone,

an electrical storage device records whether or not contact has beenmade or not made by the two switch contacts 23 and 24. When a tabletsubsequently approaches the discharge position, this tablet isselectively ejected over the edge of the die plate 15 by one of twodifferent discharge devices, according to whether or not the said tabletcontains a core. The discharge devices are twoseparate strippers 25 and26 (FIGURE 3) disposed in spaced relation respectively ejecting coredand coreless tablets. The first stripper 25 is disposed in front of, andis fitted to, a bridge-shaped support 27 having an opening 28 throughwhich tablets can pass. The stripper 25 is caused to be moved downwardsto eject a cored tablet by electromagnetic means energized by a currentdischarged by the electrical storage device so as to close the opening28. The opening 28 remains open when a coreless tablet is advancing ofthe rotating die plate so that the imperfect tablet is then dischargedlaterally by the stripper 26.

The arrangement described in the previous paragraph can be modified sothat the stripper is usually lowered and the opening 28 is closed. It isthen only occasionally, when a coreless tablet has been manufactured,that the stripper 25 is raised by the storage device into the positionshown in FIGURE 2. The coreless tablet 10 then passes through theopening 28 and finally strikes against the stripper 26 which is fixedand fed by this stripper 26 to a separate receptacle.

It is essential that the electrical impulse which is produced by theclosing of the contacts 23, 24 by a tablet in zone A (FIGURE 5) andtransmitted to the electrical storage device is retained until the sametablet has reached the discharge zone B.

If in the FIGURE 3 arrangement the tablet pressed in the zone A has acore, an electric impulse is produced by a micro-switch 30 in the mannerexplained with reference to FIGURE 4, the switch 30 corresponding to thetwo contacts 23 and 24 of FIGURE 4. If there is no core, the switch 30does not produce an impulse.

The electrical storage device comprises a series of condensers 31arranged on a disc 32 rotating in synchronism with the die plate ortable 15.

Contacts 33 are provided at the circumference of disc 32 and each ofthem is connected to one of the condensers 31. If a contact 33 slidespast a charging contact 34 with the micro-switch 30 closed, thecondenser which is now connected becomes charged. Such a charging occurseach time that a cored tablet has been compressed in the pressingoperation illustrated in FIGURE 4.

While the tablet producing the electrical impulse is travelling forwardfrom the pressing station A to the discharge station B, the disc 32 alsotravels forward and the charged condenser, through its contact 33,becomes connected with the discharge contact 35. In this position,

the condenser discharges and in so doing energizes a magnet relay 36,which closes the contacts 37 and 38 of two circuits. The circuit closedby the contact 37 energizes a solenoid 42 to operate the stripper 25.

The contacts 38, which are also closed by the magnet relay 1%, are in acircuit in which the coil of the magnet relay itself is disposed. Thus,the coil remains energized even when the condenser is discharged,provided that a circuit breaker 39 arranged in the circuit is closed.The closing of this circuit breaker 39 is effected by a lever 40, havinga bearing surface 41. The circuit breaker 39 is held in the closedposition as long as a top punch 18 is moving past the bearing surface41. The surface 41 is of such a length that the tablet producing theelectrical impulse has suflicient time to move through the opening 28 ofthe frame '27, or alternatively is rejected by stripper 25.

What I claim is:

l. A tabletting press for the manufacture of cored tablets comprising adie plate provided with a die aperture, a pair of punches movable insaid die aperture, compression rollers between which said die punchescan pass so that compression pressure is exerted on them, two ejectingdevices selectively operable one at a time for ejecting tablets producedin said die aperture, and means responsive to the loading applied tosaid punches during compression between said rollers to select one ofsaid ejecting devices.

2. A tabletting press for the manufacture of tablets by compressing acoating of comminuted material around a preformed core comprising arotatable die plate provided with a plurality of die apertures, aplurality of pairs of punches each of which pairs is movable in one ofsaid apertures, compression rollers between which each pair of punchesis movable in turn to compress comminuted material around a core, afirst ejection device for ejecting tablets having a core, a secondejection device for ejecting tablets consisting entirely of coatingmaterial, and means operable in response to the loading applied to apair of punches as they pass between said rollers to select one of saidejection devices for ejecting the tablet compressed by that pair ofpunches.

3. A tabletting press for the manufacture of tablets by compressing acoating of comminuted material around a preformed core comprising arotatable die plate provided with a plurality of die apertures, aplurality of pairs of punches each of which pairs is movable in one ofsaid apertures to produce a tablet and raise the tablet so produced outof said aperture, a resiliently supported compression roller acting onone of each pair of punches in turn to assist in compressing materialaround a pre formed core, two separate ejection devices one of which isoperable to eject tablets having cores and the other of which isoperable to eject imperfect tablets consisting entirely of coatingmaterial, and means operable in response to the differences in movementof said resiliently supported roller when acting through one of saidpunches on cored or imperfect tablets to select which of said ejectiondevices is to eject the tablet compressed with the assistance of thatpunch.

4. A tabletting press as claimed in claim 3 in which said means comprisean electric switch operable in accordance with movement of saidresiliently-supported roller to transmit electrical impulses, and astorage device adapted to receive said impulses and to act on themsubsequent to the operation of said switch.

5. A tabletting press for the manufacture of tablets by compressing acoating of comminuted material around a preformed core comprising arotatable die plate provided with a plurality of vertical die apertures,a plurality of pairs of punches each of which pairs is movable in one ofsaid apertures to compress comminuted material in said aperture and toraise the tablet so produced to the surface of said plate, a fixedstripper arranged to be engaged by tablets produced in said apertures assaid' plate rotates thereby to .eject said tablets, emovable stripperselectively movable into a position in front of said fixed stripper forejecting tablets which engage it, a resiliently-supported compressionroller displace/able by one of each pair of punches in turn inaccordance with the pressure applied to material in said apertures, andmeans operable to place said movable stripper in position whenever saidcompression roller has been displaced a predetermined amount.

6. A tabletting press for the manufacture of tablets by compressing acoating of comminuted material around a preformed core comprising arotatable die plate provided with a plurality of vertical die apertures,a plurality of pairs of punches each of which pairs is movable in one ofsaid apertures to compress comminuted material in said aperture and toraise the tablet so produced to the surface of said plate, a fixedstripper arranged to be engaged by tablets produced in said apertures assaid plate rotates thereby to eject said tablets, a movable stripperselectively movable into a position in front of said fixed stripper forejecting tablets which engage it, a resiliently-supported compressionroller displaceable by one of each pair of punches in turn in accordancewith the pressure applied to material in said apertures, a storage discrotatable in synchronisrn with said die plate, a plurality of electriccondensers carried by said disc, a first electric circuit, a chargingcontact adapted to connect each condenser in turn with said firstelectric circuit, an electric switchconnected in said first electriccircuit, means movable by said resiliently-supported compression rollerfor closing said switch when said roller is displaced by a predeterminedamount whereby an electric impulse is transmitted to one of saidcondensers through said charging contact, a secand electric circuit, adischarging contact adapted to connect each condenser in turn with saidsecond electric circuit; and an electric relay connected in said secondelectric circuit and operable by the discharge of a condenser connectedwith it through said discharging contact in order to place said movablestripper in position to engage a tablet.

7. A tabletting press as claimed in claim 6 comprising a solenoidadapted to be energized by said relay to displace said movable stripper,an electrical circuit breaker in said second electric circuit, and alever engageable by one of each pair of punches in turn to hold saidcircuit breaker in its closed position until an imperfect tablet haspassed said movable stripper.

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